Polyethylene (PE) is commonly used in manufacturing plastic pipes for gas and water supply, where high density polyethylene (HDPE) is the most common ingredient. When laying PE pipes or fixing ruptured or broken pipes, the PE pipes are typically joined using fusion welding such as butt fusion, electrofusion or hot iron fusion.
In general an electrofusion fitting comprises tubular openings adapted to receive a pipe to be connected to the fitting. An electrofusion element is arranged in the tubular opening at the inner surface to be adjacent to the outer surface of the pipe which is inserted into the fitting. A common electrofusion element consists of an electrical heating coil of resistance wire positioned some distance into the fitting and ending well before the receiving end of the joining zone of the fitting, which can be marked by some sort of rib or edge. The coil is connected to contacts for supplying electric current to the electrical heating coil. When the coil is energised, the plastic materials of the pipe and the fitting adjacent the electrofusion element melt and fuse. The thickness of both the pipe and the fitting and amount of heat is arranged such that only the inner surface of the fitting and the outer surface of the pipe melt.
Welded joints of PE pipes are however not always successful for reasons such as welding errors. Welding errors may occur due to faults in cutting the pipes, lack of- or poor scraping, particles (debris) in the welding zone, positioner problems, humidity, incorrect welding parameters, etc. A simple and secure way of testing if the joints are successfully welded is desired.
Other types of piping material such as acrylonitrile butadiene styrene (ABS), polypropylene (PP), polyvinylidene fluoride (PVDF) and polyvinyl chloride (PVC) are used for different purposes, but fittings to join these pipe types are typically different.
EP 1396672 A1 discloses certain embodiments of electrofusion.
WO 2013/136062 discloses electrofusion nipple fittings (internal fittings) for joining together two pipe sections in particular for metal pipes lined with PE pipes, that allow the integrity of the weldings to be tested
It would be appreciated to have further methods for joining and sealing pipes and testing rigorously and quickly the integrity of the seals in a non-destructive manner.